gio2: handle WOULD_BLOCK on read_nonblocking
vte3: add partially gio2conversions.h to compile vte3.

In gio2conversions.h's #ifndef macro, it adds VTE3_ prefix.
Because, __RBGIO2CONVERSIONS_H__ is alreacy defined in gtk3's one.
gio2-no-gi: disable running test

This is workaround.
vte3: fix Copyright

2011 ->
2014
   ^